25-year-old Mark Chapman, the man behind the murder, was a born-again Christian with a rare form of autism. He was obsessed with both Lennon and Holden Caulfield (the anti-hero of JD Salinger’s novel, 'The Catcher In The Rye').
Chapman had attempted the murder once before, but he changed his mind after being inspired by the film Ordinary People. After flying back home to Hawaii, he revealed his plan to his wife and made an appointment to see a clinical psychologist. However, within two months, he flew back to New York to carry out the plan.
After shooting Lennon, Chapman removed his hat and coat in preparation for his arrest, sat on the pavement and began reading his copy of The Catcher In The Rye.
In Liverpool, members of the Quarrymen, Lennon's first band, played a tribute gig at Quarry Bank school in 2010, 30 years later. Rod Davis, the band's banjo player, told the Guardian, "We're playing not to mark his death, but to celebrate his life. To talk too much of his death casts a shadow. There's more than a bit of sadness this week, so we'll be trying to focus on celebrating the John we knew".
Mark Chapman, the man responsible for Lennon's murder, is still serving time at Attica Prison for his conviction. He has just been denied parole for the ninth time in September 2010.
Here is John Lennon and his then-wife Cynthia on Feb 7, 1964, waiting at an airport in London to fly to the States.
After John Lennon's death, Yoko Ono later spread his ashes in Central Park, and no funeral ceremony was held.
Dr. Stephan Lynn, the doctor who attempted to save Lennon's life, spoke to NY's Daily News about the night of the murder: "I had no idea who the patient was. It wasn't until a nurse looked inside his wallet for identification that we realized who it was".
"In death he looked almost nothing like he looked in life," says Dr. Stephan Lynn. "He was gray, he was gaunt, he had no signs of life. He had no pulse, no blood pressure...He was not breathing. We could have at that moment declared him dead."
Fans honoured the late singer across the globe on the 30th anniversary of his death, including a gathering in New York City, opposite the Dakota Building. This is where Lennon was shot by Chapman in 1980. Yoko Ono attended an annual fund-raising concert in Tokyo in his memory.
If John Lennon were alive today, Yoko Ono believes that he would “definitely be experimenting on some new music, using the computer. I am sure it would be quite something".
The late singer’s son Sean, on the other hand, thinks his father would be making rock'n'roll. “In terms of the music he would’ve been making, it’s difficult to say. My mum has his record collection and it’s all rock’n’roll. There’s nothing in there past Elvis’ second album. So if he was still making music it’d be rock’n’roll".
Sean Lennon told NME this week that his father’s legacy is “magnificent”. He didn’t just “rest on his laurels and get fat in some palace somewhere when The Beatles broke up. He got involved in peace activism and risked his entire career making avant garde experimental music with my mum to promote his ideals".
Yoko Ono told NME that meeting John opened her eyes to rock’n’roll. “There are so many songs we loved, it’s impossible to list them" she said.
On December 14, 1980, thousands of fans gathered in New York City's Central Park to pay their final tributes to Lennon. On that same day, Yoko Ono asked the world to observe ten minutes of silence in honour of her late husband.
This image is an original illustration from the Yellow Submarine film (which can be seen in Brian Southwall and Julian Lennon's book 'Beatles Memorabilia', a collection of photographs and images of original items from throughout the band's career). While the band had very little to do with the film, John Lennon said "I liked the movie; the artwork".
Here's John Lennon in 1963 with a newly-born Julian. According to his then-wife Cynthia, John's first words when he first held his son were, "Who's going to be a little rocker, just like his dad?".
Although he had poor eyesight and was a bad driver, John Lennon drove his small Honda Monkey motorbike often. His son Julian says of the bike, "I remember Dad riding it in the driveway in Weybridge with me as the passenger...I think I was allowed to sit up front and hold the handlebars but never to actually control it".
If you want to see more images and read commentary from Julian, 'Beatles Memorabilia: The Julian Lennon Collection' is available now (published by Goodman, £25). This book was published to coincide with what would have been the musician's 70th birthday.